222 G. M. Baicson — Geology of British Columbia. 



series with the Cache Creek rocks is seen on the South Thompson, a 

 few miles above Kamloops. 



In the Gold Eange which borders on the interior plateau to the 

 north-east, the conditions found in the Coast Kange appear in many- 

 respects to be repeated. The rocks just described, but with less 

 quartzite and limestone, and probabl}'^ an added proportion of 

 volcanic material, are found in a more or less highly altered state as 

 gneisses, dioritic, hornblendic, and micaceous schists, and coarsely 

 crystalline marbles, while a belt of schistose and argillaceous beds, 

 probably the same with that already several times referred to, and 

 newer than the rocks just mentioned, is tightly folded with them, 

 giving to this axis of elevation its famed auriferous character. No 

 fossils have yet been found in the crystalline rocks of this range. 

 Eespecting the proved existence in it of a series of rocks older than 

 elsewhere known in the province, the facts are given on a succeed- 

 ing page. 



For the region to the north-east of the Gold Eange, including the 

 eastern flanks of the range, and the country between it and the 

 Eocky Mountains propei', little information has been obtained. It is 

 one exceedingly difficult of access, owing to its mountainous and 

 densely-wooded character ; but the transition from the much-flexed 

 rocks of the first- mentioned range to the comparatively little bent 

 though much broken masses of the Eocky Mountains is probably- 

 pretty abrupt. 



Structure of the Rocky Mountains. — In the Eocky Mountains we 

 have the broken margin of the undisturbed sheets of strata M'hich 

 underlie the great plains, projecting in block-like masses. In British 

 America our geological knowledge of the range is confined to the 

 observations of its extreme northern part by Sir J. Eichardson, of its 

 southern portions by Dr. Hector, a traverse on the Peace Eiver by- 

 Mr. Selwyn, and my own observations in the last-named locality 

 and on the 49th parallel. 



The most complete section is that in the vicinity of the 49th 

 parallel,^ to which I shall briefly refer, and then indicate points of 

 difference between the rocks shown in it and those of the north- 

 western continuation of the range. The total thickness of the beds 

 here seen is about 4500 feet. The lowest are impure dolomites and 

 fine dolomitic quartzites, dark purplish or grey, with a thickness of 

 700 feet or more. These may Ido of Cambrian age, and are supposed 

 to represent the Pogonip formation of Clarence King's 40th parallel 

 section.^ Overlying this is a pale grey cherty magnesian limestone, 

 with magnesian grits, estimated at 200 feet in thickness, which is 

 supposed to represent the Ute-Pogonip limestone of Silurian age of 

 the 40th parallel section. Next in order is 2000 feet or more of 

 sandstones, quartzites, and slaty rocks of various tints, but chiefly 



^ Though the investigation of the rocks of this part of the Rocky Mountains was 

 carried on quite independently, andreported on in 1875, it has been thought desirable 

 to refer the formations as far as possible to King's section, as being much the best 

 hitherto published for the Rocky Mountain Region. 



^ Geol. and Resources of 49th Parallel, p. 56. 



